The invention relates to improvements in coil springs and, more particularly, to improvements in coil springs which can be utilized with advantage in power trains between prime movers and driven parts, such as between an engine and the wheels in a motor vehicle.
It is already known to make a coil spring from round, square or rectangular wire, i.e., of wire having a truly circular or a truly polygonal cross-sectional outline. A drawback of coil springs having a truly circular cross-sectional outline is that neighboring convolutions of such springs are likely to slide relative to each other in the radial direction of the convolutions when the springs are compressed flat under load, i.e., when the neighboring convolutions actually abut each other so that the entire spring acts or is supposed to act not unlike a solid block.
A drawback of heretofore known coil springs having a polygonal (such as a square or rectangular) cross-sectional outline is that the edges between the mutually inclined portions of the external surface of one convolution are likely to and often do abut the flat portions of the external surfaces of neighboring convolutions. This can result in damage to the spring and/or in even more pronounced radial displacement of a convolution relative to the neighboring convolution or convolutions when the spring is used as a compression spring and is stressed to such an extent that the neighboring convolutions actually contact and bear against each other.